The objectives of this program are to study the role of behavioral and pharmacological variables in drug discrimination and to determine the effects of drug administration on complex behavioral processes. In drug discrimination experiments, we will use multiple schedules to extend the generality of our finding that fixed-ratio schedules produce steeper dose-effect curves than fixed-interval schedules during generalization tests. We will determine the effect of punishing incorrect responses on drug discrimination and will use concurrent variable-interval variable-interval schedules and concurrent fixed-ratio fixed-ratio schedules to determine if drug .discrimination behavior can be described in terms of the Matching Law. We also plan to begin to study the manner in which external environmental stimuli interact with interoceptive drug stimuli to produce stimulus control. The pigeon will be the primary subject, but some experiments will be replicated in rats to extend the generality of findings to another species. Phencyclidine will be the primary training drug, but some experiments will be replicated with methamphetamine to extend the generality of the findings to a second drug. The effects of substitution of other drugs for the training drug will be determined under most drug discrimination procedures. In addition to studying drugs of obvious pharmacological relevance to phencyclidine and methamphetamine, a number of other drugs will be tested for generalization to both training drugs for comparative purposes. In experiments on complex behavior, these same drugs will be studied for their effects on repeated acquisition, titrating matching-to sample, fixed-consecutive number (with and without an exteroceptive stimulus) and temporal discrimination. From these experiments important information should emerge to describe how schedule factors, environmental factors and organismic factors influence drug discrimination, as well as a description of the general pharmacology of phencyclidine, methamphetamine and related drugs. These data are relevant to both the abuse potential of these drugs and to describing the consequences of their use.